1. Field of the Invention
The present invention relates to an exposure mask used in photolithography, a method of forming a resist pattern through the use of the exposure mask, and a method of forming a thin film pattern by applying the method of forming a resist pattern.
2. Description of the Related Art
In recent years, in the field of manufacturing various devices, in order to form a thin film pattern into a desired shape, a resist pattern is widely used. Typically, the resist pattern is formed by forming a resist film, and then patterning the resist film by photolithography. More specifically, after the resist film is selectively exposed through the use of an exposure mask, the resist film is developed.
In order to achieve high resolution in a photolithography step, a large number of structural examples of the exposure mask have been proposed. More specifically, there is known an exposure mask in which an aperture and first and second aperture patterns arranged around the aperture are included, and the first and second aperture patterns are very thin patterns with a resolution limit or less for incident light, and the phases of light passing through the first and second aperture patterns are 180° different from each other (for example, refer to Japanese Examined Patent Application Publication No. H06-090506). Moreover, there is known an exposure mask in which a main aperture part and auxiliary aperture parts arranged in parallel on both sides or either side of the main aperture part are included, and the widths and positional relationship of the main aperture part and the auxiliary aperture parts are determined on the basis of conditions (numerical aperture, reduction/magnification and exposure wavelength) of an exposure apparatus (for example, refer to Japanese Patent No. 2881892). Further, there is known an exposure mask in which at least one additional line disposed at a predetermined distance away from an edge of a lithography pattern with critical dimensions and altering the edge intensity gradient of the edge is included, and the predetermined distance is proportional to the critical dimensions (for example, refer to Japanese Patent No. 3009923).